WO2018008070A1 - Inspecting device and method - Google Patents

Abstract

An inspecting device (1, 2) includes: an electromagnetic-wave generating unit (11a); an electromagnetic-wave detecting unit (16a); a reflecting part (34, 41) that can reflect an electromagnetic wave; and an adjusting means (20) that causes an electromagnetic wave emitted from the electromagnetic-wave generating unit to be introduced into the electromagnetic-wave detecting unit by way of the reflecting part, not via a subject (90), during a partial period in an inspection period during which the subject is irradiated with the electromagnetic wave and that adjusts a bias voltage applied to the electromagnetic-wave detecting unit on the basis of the detection sensitivity of the electromagnetic-wave detecting unit.

Description

Inspection apparatus and method

The present invention relates to a technical field of an inspection apparatus and method for inspecting a subject using electromagnetic waves.

As this type of device, for example, it has asymmetric forward and reverse current-voltage characteristics, operates as an oscillating element at a first operating point that exhibits negative differential resistance, and exhibits nonlinear characteristics that are not in the negative resistance region. An apparatus including an oscillation detection element that operates as a detection element at two operating points has been proposed (see Patent Document 1).

JP 2013-005115 A

The oscillation detection element described in Patent Document 1 has temperature dependence and has some individual differences. For this reason, unless the bias voltage applied to the element is appropriately set according to the use environment of the element, it may be difficult to maintain the stability of the detection operation. However, Patent Document 1 does not disclose how to set the bias voltage.

The present invention has been made in view of the above problems, for example, and an object of the present invention is to provide an inspection apparatus and method capable of realizing a stable detection operation.

In order to solve the above problems, the inspection apparatus of the present invention irradiates a subject with an electromagnetic wave generation unit, an electromagnetic wave detection unit, a reflection unit that can reflect an electromagnetic wave, and an electromagnetic wave generated from the electromagnetic wave generation unit During a part of the inspection period, the electromagnetic wave is incident on the electromagnetic wave detection unit without passing through the subject by the reflection unit, and is applied to the electromagnetic wave detection unit based on the detection sensitivity of the electromagnetic wave detection unit Adjusting means for adjusting the bias voltage to be applied.

In order to solve the above problems, an inspection method of the present invention is an inspection method in an inspection apparatus including an electromagnetic wave generation unit, an electromagnetic wave detection unit, and a reflection unit capable of reflecting an electromagnetic wave, from the electromagnetic wave generation unit The electromagnetic wave is incident on the electromagnetic wave detection unit by the reflection unit without passing through the test object during a part of the examination period in which the generated electromagnetic wave is irradiated on the test object, and the electromagnetic wave detection unit detects the electromagnetic wave. An adjustment step of adjusting a bias voltage applied to the electromagnetic wave detection unit based on sensitivity is provided.

The operation and other advantages of the present invention will be clarified from the embodiments to be described below.

It is a schematic block diagram which shows the structure of the terahertz wave measuring device which concerns on 1st Example. It is a conceptual diagram which shows the measurement operation | movement of the terahertz wave measuring device which concerns on 1st Example. It is a characteristic view which shows an example of the current-voltage characteristic of the terahertz wave detection element which concerns on 1st Example. It is a flowchart which shows the setting process of the bias voltage which concerns on 1st Example. It is a characteristic view which shows an example of the relationship between the bias voltage and detection sensitivity of the terahertz wave detection element which concerns on 1st Example. It is a schematic block diagram which shows the structure of the terahertz wave measuring device which concerns on 2nd Example. It is a conceptual diagram which shows the measurement operation | movement of the terahertz wave measuring device which concerns on 2nd Example. It is a flowchart which shows the setting process of the bias voltage which concerns on 2nd Example.

Embodiments according to the inspection apparatus and method of the present invention will be described.

(Inspection equipment)
The inspection apparatus according to the embodiment includes an electromagnetic wave generation unit, an electromagnetic wave detection unit, and an adjustment unit that adjusts a bias voltage applied to the electromagnetic wave detection unit. The adjusting means includes: a reflection part capable of reflecting electromagnetic waves; and a part of the examination period in which the electromagnetic wave generated from the electromagnetic wave generation part is irradiated on the subject without causing the reflection part to pass through the subject. Then, the light is incident on the electromagnetic wave detection unit, and the bias voltage is adjusted based on the detection sensitivity of the electromagnetic wave detection unit. An example of the electromagnetic wave is a terahertz wave.

In the inspection apparatus, the bias voltage is adjusted based on the detection sensitivity of the electromagnetic wave detection unit during a part of the inspection period (that is, during the inspection period). For example, even when the optimum value of the bias voltage changes due to a temperature change during the inspection period, the inspection apparatus can apply the optimum bias voltage to the electromagnetic wave detection unit. Therefore, according to the inspection apparatus, a stable detection operation can be realized.

In one aspect of the inspection apparatus according to the embodiment, the reflection unit is provided at least at a part of the periphery of the placement unit on which the subject is placed. The inspection apparatus further includes a scanning unit that moves the electromagnetic wave generation unit and the electromagnetic wave detection unit integrally so that the subject and the reflection unit are irradiated with the electromagnetic wave during the inspection period.

Alternatively, in another aspect of the inspection apparatus according to the embodiment, the reflection unit is disposed on the optical path of the electromagnetic wave connecting the electromagnetic wave generation unit and the subject. The inspection apparatus reflects the reflection part so that the electromagnetic wave is incident on the electromagnetic wave detection part without passing through the subject during a part of the inspection period, and the subject is irradiated with the electromagnetic wave in the other part of the inspection period. Angle changing means for changing the angle of the surface with respect to the electromagnetic wave is further provided.

According to these aspects, the bias voltage can be adjusted relatively easily during a part of the inspection period.

In another aspect of the inspection apparatus according to the embodiment, the electromagnetic wave detection unit includes an electromagnetic wave detection element having nonlinearity in current-voltage characteristics. The adjustment means sequentially changes the voltage value of the bias voltage applied to the electromagnetic wave detection unit (that is, applied to the electromagnetic wave detection element) during a part of the inspection period, so that the detection sensitivity of the electromagnetic wave detection unit is maximized. And the bias voltage is adjusted to a voltage value lower than the specified voltage value by a predetermined value. Here, the electromagnetic wave detection element may be a resonant tunnel diode. According to this aspect, it is possible to suitably detect a terahertz wave as an example of an electromagnetic wave.

(Inspection method)
The inspection method according to the embodiment is an inspection method in an inspection apparatus including an electromagnetic wave generation unit, an electromagnetic wave detection unit, and a reflection unit capable of reflecting electromagnetic waves. In the inspection method, the electromagnetic wave is incident on the electromagnetic wave detection unit without passing through the subject by the reflection unit during a part of the inspection period in which the electromagnetic wave generated from the electromagnetic wave generation unit is irradiated on the subject. An adjustment step of adjusting a bias voltage applied to the electromagnetic wave detection unit based on the detection sensitivity of the electromagnetic wave detection unit is provided.

According to the inspection method, a stable detection operation can be realized as in the inspection apparatus according to the above-described embodiment. In the inspection method, various aspects similar to the various aspects of the inspection apparatus according to the embodiment described above can be employed.

Embodiments according to the inspection apparatus of the present invention will be described with reference to the drawings. In the following embodiments, a terahertz wave measuring apparatus is taken as an example of an inspection apparatus according to the present invention. Moreover, a terahertz wave is mentioned as an example of the electromagnetic wave which concerns on this invention.

<First embodiment>
A first embodiment of a terahertz wave measuring apparatus will be described with reference to FIGS.

(Device configuration)
A configuration of the terahertz wave measuring apparatus 1 will be described with reference to FIGS. 1 and 2. FIG. 1 is a schematic configuration diagram illustrating the configuration of the terahertz wave measuring apparatus according to the first embodiment. FIG. 2 is a conceptual diagram illustrating a measurement operation of the terahertz wave measuring apparatus according to the first embodiment.

1, the terahertz wave measuring apparatus 1 includes an imaging head unit 10, a signal processing / control unit 20, a bias voltage generation unit 21, a signal amplifier 22, and a scanning mechanism 23. The terahertz wave measuring device 1 is a so-called flat bed type device (see FIG. 2A). The terahertz wave measuring apparatus 1 includes a sample stage 32 made of, for example, a fluororesin for placing the measurement object 90 and a scanner cover 33 that covers the measurement object 90.

The imaging head unit 10 includes a generation unit 11, a collimating lens 12, a beam splitter 13, an objective lens 14, a condenser lens 15, and a detection unit 16. The generating unit 11 includes a terahertz wave generating element 11a and a horn antenna 11b. The detection unit 16 includes a terahertz wave detection element 16a and a horn antenna 16b.

A bias voltage generated by the bias voltage generation unit 21 is applied to each of the terahertz wave generating element 11a and the terahertz wave detecting element 16a. A bias voltage modulated based on a predetermined reference signal is applied to the terahertz wave generating element 11a. As a result, the terahertz wave modulated at a constant frequency is emitted from the generation unit 11.

The terahertz wave emitted from the generator 11 is applied to the measurement object 90 through the collimator lens 12, the beam splitter 13, the objective lens 14, and the sample stage 32. The terahertz wave reflected by the measurement object 90 enters the detection unit 16 via the sample stage 32, the objective lens 14, the beam splitter 13, and the condenser lens 15. From the detection unit 16, a reception signal corresponding to the incident terahertz wave is output.

The scanning mechanism 23 drives the imaging head unit 10 based on the drive signal from the signal processing / control unit 20. Specifically, as shown in FIG. 2B, a so-called raster scan is performed by the scan mechanism 23. The scanning mechanism 23 further generates an imaging position signal for monitoring the irradiation position of the terahertz wave emitted from the imaging head unit 10.

The signal processing / control unit 20 receives the reception signal output from the detection unit 16 via the signal amplifier 22. When the measurement target 90 is measured by the terahertz wave measuring apparatus 1, the signal processing / control unit 20 uses the terahertz wave reception data signal generated from the reception signal output from the detection unit 16 and the scan mechanism 23. A mapped terahertz wave image is generated based on the generated imaging position signal. It should be noted that various existing aspects can be applied to the method for generating a terahertz wave image image, and therefore, detailed description thereof is omitted.

Particularly in the present embodiment, the terahertz wave measuring apparatus 1 includes a terahertz wave for reflecting the terahertz wave emitted from the generating unit 11 around the sample stage 32 and inside the housing 31 (that is, on the imaging head unit 10 side). A reflector 34 is provided.

When the terahertz wave measuring apparatus 1 is operated, as shown in FIG. 2B, the imaging head unit 10 and the terahertz wave reflecting unit 34 are overlapped when viewed in plan from above the terahertz wave measuring apparatus 1. The imaging head unit 10 is driven. When the imaging head unit 10 and the terahertz wave reflection unit 34 overlap (that is, when the imaging head 10 is positioned below the terahertz wave reflection unit 34), the terahertz wave emitted from the generation unit 11 is the measurement object 90. Without being irradiated, is reflected by the terahertz wave reflection unit 34 and enters the detection unit 16.

In the terahertz wave measuring apparatus 1, a resonant tunnel diode (Resonant Tunneling Diode: RTD) is used as the terahertz wave detecting element 16a. Here, the resonant tunnel diode as the terahertz wave detecting element 16a will be described with reference to FIG.

The resonant tunneling diode has a differential negative resistance region showing differential negative resistance characteristics in the current-voltage characteristics of its operating region (see the range from point B to point C in FIG. 3). The resonant tunneling diode further has a non-linear region exhibiting strong non-linear characteristics in the vicinity of the differential negative resistance region (see the range from point A to point B in FIG. 3).

The resonant tunneling diode functions as a terahertz wave generating element when a bias voltage corresponding to the differential negative resistance region is applied. On the other hand, the resonant tunneling diode functions as a terahertz detecting element when a bias voltage corresponding to the nonlinear region is applied.

As can be seen from FIG. 3, since the non-linear region is limited to a relatively narrow voltage range, in order for the resonant tunneling diode to operate stably as a terahertz wave detecting element, it is necessary to control the bias voltage with high accuracy. For this reason, if the bias voltage changes, or if the optimum bias voltage of the resonant tunneling diode changes due to, for example, a temperature change, the detection sensitivity may be significantly reduced (details will be described later).

Therefore, in this embodiment, based on the reception signal output from the detection unit 16 during a part of the measurement period of the measurement target 90 (that is, the period in which the imaging head unit 10 and the terahertz wave reflection unit 34 overlap). The bias voltage of the terahertz wave detecting element 16a is set (or calibrated). Hereinafter, the setting process of the bias voltage of the terahertz wave detection element 16a will be described with reference mainly to the flowchart of FIG.

(Bias voltage setting process)
In FIG. 4, first, the signal processing / control unit 20 determines whether the imaging head unit 10 is located below the terahertz wave reflection unit 34 based on the imaging position signal generated by the scanning mechanism 23. (Step S101). In this determination, when it is determined that the imaging head unit 10 is not located below the terahertz wave reflection unit 34 (step S101: No), the signal processing / control unit 20 performs the process of step S101 again. That is, the imaging head unit 10 is in a standby state until it is positioned below the terahertz wave reflection unit 34.

On the other hand, when it is determined in step S101 that the imaging head unit 10 is located below the terahertz wave reflection unit 34 (step S101: Yes), the signal processing / control unit 20 applies the terahertz wave detection element 16a. The bias voltage generation unit 21 is controlled so as to initialize the bias voltage to be executed (step S102).

Next, the signal processing / control unit 20 controls the bias voltage generation unit 21 so that the bias voltage applied to the terahertz wave detection element 16a is increased by a predetermined value ΔV1 from the current value (step S103). At this time, the signal processing / control unit 20 detects the signal amplitude of the reception signal output from the detection unit 16 (that is, the terahertz wave detection element 16a) (step S104).

Next, the signal processing / control unit 20 compares the signal amplitude detected last time with the signal amplitude detected this time, and determines whether or not the signal amplitude has decreased (step S105). Here, the signal amplitude corresponds to the detection sensitivity of the terahertz wave detection element 16a.

The detection sensitivity of the terahertz wave detection element 16a will be described with reference to FIG. Note that points A and B in FIG. 5 correspond to points A and B in FIG. As can be seen from FIG. 5, the detection sensitivity of the resonant tunneling diode as the terahertz wave detection element 16a increases as the bias voltage increases. However, when the bias voltage exceeds the voltage corresponding to point B (that is, the voltage at which the detection sensitivity is maximized), the detection sensitivity of the resonant tunneling diode is rapidly lost. That is, the resonant tunneling diode does not function as a terahertz wave detecting element.

Therefore, “when the signal amplitude is reduced” in the determination in step S105 means a case where the bias voltage applied to the terahertz wave detection element 16a exceeds the voltage at which the detection sensitivity is maximized. When it is determined that the signal amplitude has not decreased (step S105: No), the signal processing / control unit 20 performs the process of step S103. Note that the initial value of the signal amplitude detected last time may be set to zero, for example. With this configuration, even when the determination in step S105 is performed for the first time after the bias voltage is initialized by the process in step S102, the process proceeds to “S105: No” and the process in step S103 is performed.

On the other hand, if it is determined in step S105 that the signal amplitude has decreased (step S105: Yes), the signal processing / control unit 20 performs bias so that the bias voltage is reduced by a predetermined value ΔV2 from the current value. The voltage generator 21 is controlled (step S106).

Here, the significance of reducing the bias voltage by a predetermined value ΔV2 from the current value will be described with reference to FIG. Ideally, if a voltage corresponding to point B in FIG. 5 is applied as a bias voltage to the terahertz wave detection element 16a, the detection sensitivity of the terahertz wave detection element 16a can be maximized. However, if the bias voltage fluctuates during measurement of the measurement object 90, for example, the resonant tunnel diode may not function as the terahertz wave detection element 16a.

Therefore, in this embodiment, the bias voltage is lower than the voltage at which the detection sensitivity is maximized (the voltage corresponding to the range from point D to point E in FIG. 5) by a predetermined value ΔV2. The bias voltage is reduced. With this configuration, it is possible to achieve both the stability of the operation of the terahertz wave detection element 16a and good detection sensitivity.

The predetermined value ΔV1 may be appropriately set in consideration of, for example, the time required for the bias voltage setting process, the voltage error of the bias voltage generation unit 21, and the like. The predetermined value ΔV2 may be appropriately set in consideration of, for example, the predetermined value ΔV1 and the voltage-detection sensitivity characteristic related to the terahertz wave detection element 16a.

(Technical effect)
In this embodiment, the above-described bias voltage setting process is repeated. As a result, the bias voltage is reset (or calibrated) every time the imaging head unit 10 is positioned below the terahertz wave reflection unit 34. For this reason, an optimal bias voltage can always be applied to the terahertz wave detecting element 16a, and the stable measurement operation of the terahertz wave measuring apparatus 1 can be realized.

The “terahertz wave generating element 11a”, the “terahertz wave detecting element 16a”, the “terahertz wave reflecting unit 34”, the “signal processing / control unit 20”, and the “measurement object 90” according to the present embodiment are each represented by the present invention. Is an example of “electromagnetic wave generation unit”, “electromagnetic wave detection unit”, “reflection unit”, “adjusting means”, and “subject”.

The generation unit 11 may include a plurality of terahertz wave generation elements 11a and horn antennas 11b arranged in an array. Similarly, the detection unit 16 may include a plurality of terahertz wave detection elements 16a and horn antennas 16b arranged in an array. Further, instead of the horn antenna, a hemispherical or super hemispherical silicon lens may be used. Instead of the beam splitter 13, for example, a half mirror, a combination of a polarizer and a quarter wavelength plate, or the like can be applied.

<Second embodiment>
A second embodiment of the terahertz wave measuring apparatus will be described with reference to FIGS. The second embodiment is the same as the first embodiment described above except that the configuration of the terahertz wave measuring apparatus and part of the bias voltage setting process are different. Therefore, in the second embodiment, the description overlapping with that of the first embodiment is omitted, and the common portions in the drawing are denoted by the same reference numerals and only FIGS. 6 to 8 are basically different only. The description will be given with reference.

(Device configuration)
The configuration of the terahertz wave measuring apparatus 2 will be described with reference to FIGS. 6 and 7. FIG. 6 is a schematic configuration diagram illustrating the configuration of the terahertz wave measuring apparatus according to the second embodiment. FIG. 7 is a conceptual diagram showing the measurement operation of the terahertz wave measuring apparatus according to the second embodiment.

6, the terahertz wave measuring apparatus 2 includes an imaging head unit 10 ′, a signal processing / control unit 20, a bias voltage generation unit 21, a signal amplifier 22, a polygon mirror driving unit 24, a polygon mirror 41, and an objective lens 42. It is configured.

In this embodiment, when the measurement target 90 is measured, the polygon mirror 41 is rotated by the polygon mirror drive unit 24, so that the terahertz wave emitted from the generation unit 11 scans the measurement target 90 (see FIG. 7).

As can be seen from FIG. 7, when the polygon mirror 41 rotates, the reflection surface of the polygon mirror 41 faces the imaging head unit 10 ′ during a part of the period, so that the terahertz wave emitted from the generation unit 11 is measured. The object 90 is not irradiated, but is reflected by the polygon mirror 41 and enters the detector 16 (see FIG. 7D).

In the present embodiment, a part of the measurement period of the measurement object 90 (that is, the terahertz wave emitted from the generation unit 11 is reflected by the polygon mirror 41 and is not irradiated on the measurement object 90, and the detection unit 90 16), the bias voltage of the terahertz wave detection element 16a is set (or calibrated) based on the reception signal output from the detection unit 16. Hereinafter, the setting process of the bias voltage of the terahertz wave detection element 16a will be described with reference to the flowchart of FIG.

(Bias voltage setting process)
In FIG. 8, first, the signal processing / control unit 20 stores the current bias voltage as the memory 1 (that is, the value of the variable “memory 1” relating to the bias voltage is set as the current bias voltage) (step S201). ).

Next, the signal processing / control unit 20 refers to, for example, the drive signal of the polygon mirror drive unit 24 to determine whether or not the polygon mirror 41 faces the imaging head unit 10 ′ (that is, emitted from the generation unit 11). Whether the incident angle of the terahertz wave with respect to the reflection surface of the polygon mirror 41 is 0 degree or not is determined (step S202).

If it is determined in step S202 that the polygon mirror 41 does not face the imaging head unit 10 '(step S202: No), the signal processing / control unit 20 performs the process of step S202 again. During the period until the polygon mirror 41 faces the imaging head unit 10 ′, the measurement object 90 is measured.

On the other hand, when it is determined in step S202 that the polygon mirror 41 is directly facing the imaging head unit 10 '(step S202: Yes), the signal processing / control unit 20 is applied to the terahertz wave detection element 16a. The bias voltage generator 21 is controlled so as to initialize the bias voltage to be initialized (step S203).

Next, the signal processing / control unit 20 controls the bias voltage generation unit 21 so that the bias voltage applied to the terahertz wave detection element 16a is increased by a predetermined value ΔV1 from the current value (step S204).

Next, the signal processing / control unit 20 determines whether or not the polygon mirror 41 is facing the imaging head unit 10 '(step S205). In this determination, when it is determined that the polygon mirror 41 is directly facing the imaging head unit 10 ′ (step S205: Yes), the signal processing / control unit 20 detects the detection unit 16 (that is, the terahertz wave detection element 16a). The signal amplitude of the received signal output from is detected (step S206).

Next, the signal processing / control unit 20 compares the signal amplitude detected last time with the signal amplitude detected this time, and determines whether or not the signal amplitude has decreased (step S207). In this determination, when it is determined that the signal amplitude has not decreased (step S207: No), the signal processing / control unit 20 performs the process of step S204.

On the other hand, if it is determined in step S207 that the signal amplitude has decreased (step S207: Yes), the signal processing / control unit 20 performs bias so that the bias voltage is reduced from the current value by a predetermined value ΔV2. The voltage generator 21 is controlled (step S208).

If it is determined in step S205 that the polygon mirror 41 does not face the imaging head unit 10 '(step S205: No), the signal processing / control unit 20 stores the current bias voltage as the memory 2. (That is, the value of the variable “memory 2” relating to the bias voltage is set as the current bias voltage) (step S209).

Subsequently, the signal processing / control unit 20 controls the bias voltage generation unit 21 so that the bias voltage returns to the value recorded in the memory 1 (step S210). When it is determined in step S205 that the polygon mirror 41 does not face the imaging head unit 10 ′, the terahertz wave emitted from the generation unit 11 is irradiated to the measurement object 90. At this time, by returning the bias voltage to the value stored in the memory 1, the measurement of the measurement object 90 is appropriately performed.

Next, the signal processing / control unit 20 determines whether or not the polygon mirror 41 is facing the imaging head unit 10 '(step S211). In this determination, when it is determined that the polygon mirror 41 does not face the imaging head unit 10 ′ (step S211: No), the signal processing / control unit 20 performs the process of step S211 again. During the period until the polygon mirror 41 faces the imaging head unit 10 ′, the measurement object 90 is measured.

If it is determined in step S211 that the polygon mirror 41 is directly facing the imaging head unit 10 '(step S211: Yes), the signal processing / control unit 20 has the bias voltage recorded in the memory 2. The bias voltage generation unit 21 is controlled so as to be a value (step S212), and the process of step S206 is performed.

(Technical effect)
In the present embodiment, in particular, when the polygon mirror 41 faces the imaging head unit 10 ′, which is generated in principle, the incident angle of the terahertz wave emitted from the generation unit 11 with respect to the reflection surface of the polygon mirror 41 is increased. At 0 degree), the bias voltage of the terahertz wave detecting element 16a is reset (or calibrated). When the polygon mirror 41 faces the imaging head unit 10 ′, it corresponds to the dead time of the measurement period, so that the measurement time is not extended by resetting the bias voltage.

The “polygon mirror 41” according to the present embodiment is another example of the “reflecting portion” according to the present invention. The “polygon mirror drive unit 24” according to the present embodiment is an example of the “angle changing unit” according to the present invention.

The polygon mirror 41 is not limited to a quadrangle (see FIG. 6). For the objective lens 42, for example, an f-θ lens may be used.

The present invention is not limited to the above-described embodiment, and can be appropriately changed without departing from the spirit or idea of the invention that can be read from the claims and the entire specification, and an inspection apparatus and method with such a change. Is also included in the technical scope of the present invention.

DESCRIPTION OF SYMBOLS 1, 2 ... Terahertz wave measuring device 10, 10 '... Imaging head part, 11a ... Terahertz wave generation element, 16a ... Terahertz wave detection element, 20 ... Signal processing / control part, 21 ... Bias voltage generation part, 22 ... Signal Amplifier, 23 ... Scanning mechanism, 24 ... Polygon mirror driving portion, 34 ... Reflecting portion, 41 ... Polygon mirror, 90 ... Measurement object

Claims (7)

An electromagnetic wave generator,
An electromagnetic wave detection unit;
A reflective part capable of reflecting electromagnetic waves;
The electromagnetic wave generated from the electromagnetic wave generation unit is incident on the electromagnetic wave detection unit without passing through the test object by the reflection unit during a part of the examination period in which the test object is irradiated with the electromagnetic wave. An adjusting means for adjusting a bias voltage applied to the electromagnetic wave detection unit based on the detection sensitivity of the electromagnetic wave detection unit;
An inspection apparatus comprising: The reflecting portion is provided at least at a part of the periphery of the placement portion on which the subject is placed;
The scanning apparatus according to claim 1, further comprising a scanning unit that moves the electromagnetic wave generation unit and the electromagnetic wave detection unit as a unit so that the electromagnetic wave is irradiated to the subject and the reflection unit during the examination period. The inspection device described. The reflecting portion is disposed on an optical path of the electromagnetic wave that connects the electromagnetic wave generating portion and the subject,
Reflection of the reflection unit is performed such that the electromagnetic wave is incident on the electromagnetic wave detection unit without passing through the subject during the partial period, and the electromagnetic wave is irradiated on the subject during the other period of the examination period. The inspection apparatus according to claim 1, further comprising an angle changing unit that changes an angle of the surface with respect to the electromagnetic wave. The electromagnetic wave detection unit includes an electromagnetic wave detection element having nonlinearity in current-voltage characteristics,
The adjusting means sequentially changes the voltage value of the bias voltage during the partial period to specify a voltage value at which the detection sensitivity is maximized, and sets the voltage value to a voltage value lower than the specified voltage value by a predetermined value. The inspection apparatus according to claim 1, wherein the bias voltage is adjusted. The inspection apparatus according to claim 4, wherein the electromagnetic wave detection element is a resonant tunnel diode. The inspection apparatus according to claim 1, wherein the electromagnetic wave is a terahertz wave. An inspection method in an inspection apparatus comprising an electromagnetic wave generation unit, an electromagnetic wave detection unit, and a reflection unit capable of reflecting electromagnetic waves,
The electromagnetic wave generated from the electromagnetic wave generation unit is incident on the electromagnetic wave detection unit without passing through the test object by the reflection unit during a part of the examination period in which the test object is irradiated with the electromagnetic wave. An inspection method comprising: an adjustment step of adjusting a bias voltage applied to the electromagnetic wave detection unit based on detection sensitivity of the electromagnetic wave detection unit.

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